1. Field of the Invention
The invention relates to an elastomeric strip of improved flexibility, preferably of the channel-shaped type, for sealing and/or decorative purposes such as, for example, for gripping and covering edge flanges surrounding an opening in a vehicle body.
The invention further relates to a method of manufacturing the elastomeric strip of improved flexibility by reinforcing regions of longitudinally displaceable frame portions of the support frame of the strip with a degradable material(s), arranging the reinforced support frame in a position to be coated, coating the reinforced support frame with an elastomeric material, and then degrading selective regions of the degradable reinforcing material(s).
2. Description of the Prior Art
Coating processes are known for coating elastomeric material onto a support frame. The support frame may comprise, for example, a slotted metal frame having frangible metal webs on at least one side thereof, a ladder-like frame having a plurality of parallel, spaced apart metal rungs secured to a textile yarn or string on the sides thereof, or a serpentine or looped wire frame interwoven on the sides thereof with a yarn or string material. In one coating process, the support frame is fed through an extrusion die at a high rate of speed and an elastomeric material extruded thereon. At the high rate of speed involved, the hydraulic forces of the elastomeric material acting on the support frame in the extrusion die could cause possible longitudinal displacement of portions of the support frame and jamming of the extrusion die. Such longitudinal displacement was prevented in the slotted metal support frame by the metal webs and in the ladder and looped wire support frames by the yarn or string material which is interwoven with the ladder rungs or wire loops. Although the metal webs and yarn or string solved the problem of longitudinal displacement and jamming during extrusion, they presented another problem, that of limiting the longitudinal displacement of portions of the support frame and hence the flexibility of the sealing strip during installation and use thereof. This problem of limited or insufficient flexibility is particularly acute with the advent of smaller cars in which the sealing strip is required to negotiate inside, outside and lateral curved flanges of tighter radii. The sealing strip of limited flexibility cannot faithfully follow or accomodate small curves or radii resulting in buckling of the sealing strip and the formation of a leakage space between the flange and sealing strip. In those applications where the sealing strip is channel-shaped and has an elongated sealing bulb secured thereto, severe bending causes distortion of the bulb and possible leakage between the bulb and surface in sealing engagement therewith.
The problem of limited strip flexibility was solved for elastomeric strips having a slotted metal support frame by breaking the metal side webs. It was also solved for strips having a serpentine wire frame by conducting an electrical current through the wire which is heated sufficiently to burn the yarn or string knots or loops encircling the wire. A disadvantage of these solutions is that all of the material preventing longitudinal displacement of the support frame is destroyed or degraded causing excessive elongation of the strip to occur during application. Later, the applied strip retracts resulting in the formation of leakage areas.